jsp+servlet+jdbc實現對數據庫的增刪改查

時間 2019-11-19

標籤 jsp+servlet+jdbc jsp servlet jdbc 實現數據庫增刪欄目 JSP 简体版

原文原文鏈接

1、JSP和Servlet的簡單介紹：javascript

一、Servlet和JSP簡介：
css

　　Java開發Web應用程序時用到的技術主要有兩種，即Servlet和JSP，Servlet是在服務器端執行的Java程序，一個被稱爲Servlet容器的程序（其實就是服務器）負責執行Java程序，而JSP(Java Server Page)則是一個頁面，由JSP容器負責執行。html

二、Servlet和JSP的區別：
java

Servlet以Java程序爲主，輸出HTML代碼時須要使用out.println函數，也就是說Java中內嵌HTML；而JSP則以HTML頁面爲主，須要寫Java代碼時則在頁面中直接插入Java代碼，即HTML中內嵌Java。mysql

三、MVC模型web

MVC模型就是將數據、邏輯處理、用戶界面分離的一種方法。sql

1）、M(Model，模型)：用於數據處理、邏輯處理數據庫

2）、V(View，視圖)：用於顯示用戶界面tomcat

3）、C(Controller，控制器)：根據客戶端的請求控制邏輯走向和畫面服務器

而在Java中，MVC這三個部分則分別對應於 JavaBeans、JSP和Servlet

1）、M = JavaBeans：用於傳遞數據，擁有與數據相關的邏輯處理

2）、V = JSP：從Model接收數據並生成HTML

3）、C = Servlet：接收HTTP請求並控制Model和View

2、代碼演示，實現了book的添加刪除和修改功能

一、環境的配置

myeclipse+tomcat+MySQL

二、Book中bean類：提供字段屬性，並提供get/set方法

package example.bean.book; public class Book { // 編號 
  private int id; // 圖書名稱 
  private String name; // 價格 
  private double price; // 數量 
  private int bookCount; // 做者 
  private String author; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public double getPrice() { return price; } public void setPrice(double price) { this.price = price; } public int getBookCount() { return bookCount; } public void setBookCount(int bookCount) { this.bookCount = bookCount; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } }

三、Servlet類

1)、FindServlet.java

package example.servlet.book; import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; import java.util.ArrayList; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import example.bean.book.Book;//導入包下的Book類 /** * Servlet implementation class FindServlet */
public class FindServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse * response) */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { try { // 加載數據庫驅動，註冊到驅動管理器 
      Class.forName("com.mysql.jdbc.Driver"); // 數據庫鏈接字符串 
      String url = "jdbc:mysql://localhost:3306/db_book?useUnicode=true&characterEncoding=utf-8"; // 數據庫用戶名 
      String username = "root"; // 數據庫密碼 
      String password = ""; // 建立Connection鏈接 
      Connection conn = DriverManager.getConnection(url, username, password); // 添加圖書信息的SQL語句 
      String sql = "select * from tb_books"; // 獲取Statement 
      Statement statement = conn.createStatement(); ResultSet resultSet = statement.executeQuery(sql); List<Book> list = new ArrayList<Book>(); while (resultSet.next()) { Book book = new Book(); book.setId(resultSet.getInt("id")); book.setName(resultSet.getString("name")); book.setPrice(resultSet.getDouble("price")); book.setBookCount(resultSet.getInt("bookCount")); book.setAuthor(resultSet.getString("author")); list.add(book); } request.setAttribute("list", list); resultSet.close(); statement.close(); conn.close(); } catch (Exception e) { e.printStackTrace(); } request.getRequestDispatcher("book_list.jsp") .forward(request, response); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse * response) */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub 
 doGet(request, response); } }

2)、UpdateServlet.java類

package example.servlet.book; import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * Servlet implementation class UpdateServlet */
public class UpdateServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse * response) */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { int id = Integer.valueOf(request.getParameter("id")); int bookCount = Integer.valueOf(request.getParameter("bookCount")); try { // 加載數據庫驅動，註冊到驅動管理器 
      Class.forName("com.mysql.jdbc.Driver"); // 數據庫鏈接字符串 
      String url = "jdbc:mysql://localhost:3306/db_book"; // 數據庫用戶名 
      String username = "root"; // 數據庫密碼 
      String password = ""; // 建立Connection鏈接 
      Connection conn = DriverManager.getConnection(url, username, password); // 更新SQL語句 
      String sql = "update tb_books set bookcount=? where id=?"; // 獲取PreparedStatement 
      PreparedStatement ps = conn.prepareStatement(sql); // 對SQL語句中的第一個參數賦值 
      ps.setInt(1, bookCount); // 對SQL語句中的第二個參數賦值 
      ps.setInt(2, id); // 執行更新操做 
 ps.executeUpdate(); // 關閉PreparedStatement 
 ps.close(); // 關閉Connection 
 conn.close(); } catch (Exception e) { e.printStackTrace(); } // 重定向到FindServlet 
    response.sendRedirect("FindServlet"); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse * response) */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub 
 doGet(request, response); } }

3）、DeleteServlet類

package example.servlet.book; import java.io.IOException; import java.sql.Connection; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import example.dao.book.BookJdbcDao; import example.dao.book.ConnectionFactory; /** * Servlet implementation class DeleteServlet */
public class DeleteServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse * response) */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { int id = Integer.valueOf(request.getParameter("id")); try { //     // 加載數據庫驅動，註冊到驅動管理器 // Class.forName("com.mysql.jdbc.Driver"); //     // 數據庫鏈接字符串 // String url = "jdbc:mysql://localhost:3306/db_book"; //     // 數據庫用戶名 // String username = "root"; //     // 數據庫密碼 // String password = ""; //     // 建立Connection鏈接 // Connection conn = DriverManager.getConnection(url, username, // password); //     // 刪除圖書信息的SQL語句 // String sql = "delete from tb_books where id=?"; //     // 獲取PreparedStatement // PreparedStatement ps = conn.prepareStatement(sql); //     // 對SQL語句中的第一個佔位符賦值 // ps.setInt(1, id); //     // 執行更新操做 // ps.executeUpdate(); //     // 關閉PreparedStatement // ps.close(); //     // 關閉Connection // conn.close(); 
      BookJdbcDao bookDao=new BookJdbcDao(); Connection conn=ConnectionFactory.getInstance().getConnection(); bookDao.delete(conn,id); } catch (Exception e) { e.printStackTrace(); } // 重定向到FindServlet 
    response.sendRedirect("FindServlet"); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse * response) */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

四、servlet訪問url映射配置：

　　因爲客戶端是經過URL地址訪問web服務器中的資源，因此Servlet程序若想被外界訪問，必須把servlet程序映射到一個URL地址上，這個工做在web.xml文件中使用<servlet>元素和<servlet-mapping>元素完成，<servlet>元素用於註冊Servlet，它包含有兩個主要的子元素：<servlet-name>和<servlet-class>，分別用於設置Servlet的註冊名稱和Servlet的完整類名。

　　一個<servlet-mapping>元素用於映射一個已註冊的Servlet的一個對外訪問路徑，它包含有兩個子元素：<servlet-name>和<url-pattern>，分別用於指定Servlet的註冊名稱和Servlet的對外訪問路徑。另外：同一個Servlet能夠被映射到多個URL上，即多個<servlet-mapping>元素的<servlet-name>子元素的設置值能夠是同一個Servlet的註冊名。

eg：上例中的web.xml

<?xml version="1.0" encoding="UTF-8"?> 
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> 
 <display-name>JdbcConnection</display-name> 
 <welcome-file-list> 
  <welcome-file>index.html</welcome-file> 
  <welcome-file>index.htm</welcome-file> 
  <welcome-file>index.jsp</welcome-file> 
  <welcome-file>default.html</welcome-file> 
  <welcome-file>default.htm</welcome-file> 
  <welcome-file>default.jsp</welcome-file> 
 </welcome-file-list> 
 <servlet> 
  <description></description> 
  <display-name>FindServlet</display-name> 
  <servlet-name>FindServlet</servlet-name> 
  <servlet-class>example.servlet.book.FindServlet</servlet-class> 
 </servlet> 
 <servlet-mapping> 
  <servlet-name>FindServlet</servlet-name> 
  <url-pattern>/FindServlet</url-pattern> 
 </servlet-mapping> 
 <servlet> 
  <description></description> 
  <display-name>UpdateServlet</display-name> 
  <servlet-name>UpdateServlet</servlet-name> 
  <servlet-class>example.servlet.book.UpdateServlet</servlet-class> 
 </servlet> 
 <servlet-mapping> 
  <servlet-name>UpdateServlet</servlet-name> 
  <url-pattern>/UpdateServlet</url-pattern> 
 </servlet-mapping> 
 <servlet> 
  <description></description> 
  <display-name>DeleteServlet</display-name> 
  <servlet-name>DeleteServlet</servlet-name> 
  <servlet-class>example.servlet.book.DeleteServlet</servlet-class> 
 </servlet> 
 <servlet-mapping> 
  <servlet-name>DeleteServlet</servlet-name> 
  <url-pattern>/DeleteServlet</url-pattern> 
 </servlet-mapping> 
</web-app>

五、jsp頁面

1）、index.jsp web頁面主界面

<%@page import="java.sql.SQLException"%> 
<%@page import="java.sql.DriverManager"%> 
<%@page import="java.sql.Connection"%> 
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> 
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 
<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 
<title>添加圖書信息</title> 
  
<script type="text/javascript"> function check(form) { with (form) { if (name.value == "") { alert("圖書名稱不能爲空"); return false; } if (price.value == "") { alert("圖書價格不能爲空"); return false; } if (author.value == "") { alert("做者不能爲空"); return false; } } } </script> 
  
</head> 
  
  
<body> 
  
<form action="addbook.jsp" method="post" onsubmit="check(this)"> 
  <table align="center" width="450"> 
    <tr> 
      <td align="center" colspan="2"> 
        <h2>添加圖書信息</h2> 
        <hr> 
      </td> 
    </tr> 
  
    <tr> 
      <td align="right">圖書名稱：</td> 
      <td><input type="text" name="name"></td> 
    </tr> 
  
    <tr> 
      <td align="right">價 格：</td> 
      <td><input type="text" name="price"></td> 
    </tr> 
  
    <tr> 
      <td align="right">數 量：</td> 
      <td><input type="text" name="bookCount" /></td> 
    </tr> 
  
    <tr> 
      <td align="right">做 者：</td> 
      <td><input type="text" name="author" /></td> 
    </tr> 
    <tr> 
      <td align="center" colspan="2"><input type="submit" value="添　加"> 
      </td> 
    </tr> 
  </table> 
</form> 
  
<h2 align="center"> 
  <a href="FindServlet">查詢圖書信息</a> 
</h2> 
  
</body> 
</html>

2)、addbook.jsp 添加書籍成功或者失敗後的顯示頁面

<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> 
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 
  
<%@page import="java.sql.Connection"%> 
<%@page import="java.sql.DriverManager"%> 
<%@page import="java.sql.PreparedStatement"%> 
<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 
<title>添加結果</title> 
</head> 
<body> 
  <% request.setCharacterEncoding("utf-8"); %> 
  <jsp:useBean id="book" class="example.bean.book.Book"></jsp:useBean> 
  <jsp:setProperty property="*" name="book" /> 
  <% 
    try { // 加載數據庫驅動，註冊到驅動管理器 
      Class.forName("com.mysql.jdbc.Driver"); // 數據庫鏈接字符串 
      String url = "jdbc:mysql://localhost:3306/db_book?useUnicode=true&characterEncoding=utf-8"; // 數據庫用戶名 
      String username = "root"; // 數據庫密碼 
      String password = ""; // 建立Connection鏈接 
      Connection conn = DriverManager.getConnection(url, username, password); // 添加圖書信息的SQL語句 
      String sql = "insert into tb_books(name,price,bookCount,author) values(?,?,?,?)"; // 獲取PreparedStatement 
      PreparedStatement ps = conn.prepareStatement(sql); // 對SQL語句中的第1個參數賦值 
      ps.setString(1, book.getName()); // 對SQL語句中的第2個參數賦值 
      ps.setDouble(2, book.getPrice()); // 對SQL語句中的第3個參數賦值 
      ps.setInt(3, book.getBookCount()); // 對SQL語句中的第4個參數賦值 
      ps.setString(4, book.getAuthor()); // 執行更新操做，返回所影響的行數 
      int row = ps.executeUpdate(); // 判斷是否更新成功 
      if (row > 0) { // 更新成輸出信息 
        out.print("成功添加了 " + row + "條數據！"); } // 關閉PreparedStatement，釋放資源 
 ps.close(); // 關閉Connection，釋放資源 
 conn.close(); } catch (Exception e) { out.print("圖書信息添加失敗！"); e.printStackTrace(); } %> 
  <br> 
  <a href="index.jsp">返回</a> 
</body> 
</html>

3)、book_list.jsp 查找全部書籍信息的顯示頁面，以表格方式顯示

<!--<%@page import="sun.awt.SunHints.Value"%>--> 
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> 
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 
  
<%@page import="java.util.List"%> 
<%@page import="example.bean.book.Book"%> 
<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 
<title>全部圖書信息</title> 
<style type="text/css"> td { font-size: 12px; } h2 { margin: 0px } </style> 
<script type="text/javascript"> function check(form) { with (form) { if (bookCount.value == "") { alert("請輸入更新數量！"); return false; } if (isNaN(bookCount.value)) { alert("格式錯誤！"); return false; } return true; } } </script> 
  
  
</head> 
<body> 
  <table align="center" width="450" border="1" height="180" bordercolor="white" bgcolor="black" cellpadding="1" cellspacing="1"> 
    <tr bgcolor="white"> 
      <td align="center" colspan="7"> 
        <h2>全部圖書信息</h2> 
      </td> 
    </tr> 
    <tr align="center" bgcolor="#e1ffc1"> 
      <td><b>ID</b></td> 
      <td><b>圖書名稱</b></td> 
      <td><b>價格</b></td> 
      <td><b>數量</b></td> 
      <td><b>做者</b></td> 
      <td><b>修改</b></td> 
      <td><b>刪除</b></td> 
    </tr> 
    <% 
      // 獲取圖書信息集合 
      List<Book> list = (List<Book>) request.getAttribute("list"); // 判斷集合是否有效 
      if (list == null || list.size() < 1) { out.print("沒有數據！"); } else { // 遍歷圖書集合中的數據 
        for (Book book : list) { %> 
    <tr align="center" bgcolor="white"> 
      <td><%=book.getId()%></td> 
      <td><%=book.getName()%></td> 
      <td><%=book.getPrice()%></td> 
      <td><%=book.getBookCount()%></td> 
      <td><%=book.getAuthor()%></td> 
      <td > 
        <form style="align:center; background-color: gray" action="UpdateServlet" method="post" onsubmit="return check(this);"> 
           <input type="hidden" name="id" value="<%=book.getId()%>"> <input type="text" name="bookCount" size="3"> 
           <input type="submit" value="修改數量"> 
        </form> 
      </td> 
      <td> 
      <a href="DeleteServlet?id=<%=book.getId()%>">刪除</a> 
      </td> 
  
  
    </tr> 
    <% } } %> 
  </table> 
  <h2 align="center"> 
    <a href="index.jsp">返回添加圖書信息頁面</a> 
  </h2> 
  
</body> 
</html>

六、jdbc簡單的封裝

1）、ConnectionFactory.java工廠類

package example.dao.book; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; public class ConnectionFactory { private String driverClassName = "com.mysql.jdbc.Driver"; private String url = "jdbc:mysql://localhost:3306/db_book?useUnicode=true&characterEncoding=utf-8"; private String userName = "root"; private String password = ""; private static ConnectionFactory connectionFactory=null; private ConnectionFactory() { try { Class.forName(driverClassName); } catch (ClassNotFoundException e) { e.printStackTrace(); } } public Connection getConnection() throws SQLException { return DriverManager.getConnection(url, userName, password); } public static ConnectionFactory getInstance() { if (null==connectionFactory) { connectionFactory=new ConnectionFactory(); } return connectionFactory; } }

2）、BookJdbcDao.java數據庫操做封裝類

package example.dao.book; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import example.bean.book.Book; public class BookJdbcDao { private PreparedStatement ptmt = null; private ResultSet rs = null; public BookJdbcDao() { } public void findAll(Connection conn) throws SQLException { //to do  } public void delete(Connection conn, int id) throws SQLException { String sql = "delete from tb_books where id=?"; try{ ptmt = conn.prepareStatement(sql); // 對SQL語句中的第一個佔位符賦值 
      ptmt.setInt(1, id); // 執行更新操做 
 ptmt.executeUpdate(); }finally{ if (null!=ptmt) { ptmt.close(); } if (null!=conn) { conn.close(); } } } public void update(Connection conn, int id ,int bookcount) throws SQLException { //to do 
 } }